1. Technical Field
The disclosed subject matter relates to coupling of speakers with an integrated circuit (IC).
2. Description of the Related Art
A spurt of advancement in various technologies has led to the genesis of highly sophisticated integrated circuits (ICs). In particular, the ICs manufactured for mobile handsets are in high demand due to an increase in the number of mobile phone users. A typical IC used in mobile phones, hereinafter referred to as mobile IC, includes a number of pin interfaces coupled with respective driver circuits. The pin interfaces are used to couple the mobile IC with other components, such as speakers, external memory and battery, to perform various input and output functions. Therefore, the pin interfaces of the mobile IC facilitate implementation of various features, such as audio/video calls, extended memory, Bluetooth, camera, etc., in a mobile phone.
More the number of pin interfaces that can be made available on a mobile IC, more would be the number of functionalities that can be provided. However, addition of pin interfaces is constrained by the space available on the mobile IC. Also, these pin interfaces are coupled to driver circuits, which occupy a lot of space in the mobile IC. Moreover, functions such as operations related to transceiver circuits and power management units (PMUs) of the mobile phone use a fixed number of pin interfaces. Therefore, efforts are being made to reduce the number of pin interfaces used for other functionalities, such as for coupling of speakers with a mobile IC.
The speakers generally supported by mobile IC pin interfaces include a high power speaker, a low power handset speaker, and earphone speakers. The handset speaker facilitates normal listening of voice calls, while the earphone speakers provide stereo playback of audio in audio/video applications, such as radio broadcast, music files and videos. On the other hand, the high power speaker is used for certain operations such as playback of Hi-Fi ring tones and sound amplification of voice calls. Several attempts have been assayed in the past to reduce the count of pin interfaces for the coupling of speakers with a mobile IC, for example by using shared driver circuits. However, such attempts escalated cross talk between the speakers and an unwanted variation in the performance metrics, such as noise, linearity, and power supply rejection ratio, of the mobile IC. Moreover, when shared driver circuit configurations were used, operation of the mobile IC over the entire range of supply voltage provided to the mobile IC became unreliable.